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Tualatin River Basin Rapid Stream Assessment Technique (RSAT)

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Tualatin River Basin Rapid Stream Assessment Technique (RSAT) Tualatin River Basin Rapid Stream Assessment Technique (RSAT) Watersheds 2000 Field Methods Clean Water Services Watershed Management Division 155 North First Ave Hillsboro, OR 97124 July 2000 Acknowledgements Rapid Stream Assessment Technique Adapted from Rapid Stream Assessment Technique (RSAT) Field Methods 1996 Montgomery County Department of Environmental Protection Division of Water Resources Management Montgomery County, Maryland and Department of Environmental Programs Metropolitan Washington Council of Governments 777 North Capitol St., NE Washington, DC 20002 Rapid Stream Assessment Technique Table of Contents Page I. Introduction.............................................................................. 1 I. Tualatin Basin RSAT Field Protocols..................................... 2 A. Field Survey Preparation, Planning, and Data Organization......................2 A. Stream Flow Characterization Valley Profile, Reach Gradient..................3 Velocity Volume/discharge A. Stream Cross Section Characterization ........................................................4 Bankfull Width Bed Width Wetted Width Average Wetted Depth Maximum Bankfull Depth Over Bank Height Bankfull Height Bank Angle Ratio A. Stream Channel Characterization..................................................................7 Bank Material Bank Stability and Undercut Banks Recent Bed Downcutting Dominant Bed Material Deposition Material Embeddedness A. Water Quality.................................................................................................11 Substrate Fouling Water Quality Meter Readings, Color and Odor Presence of Algae Sampling A. Physical In-Stream Habitat...........................................................................14 Riffle Substrate Material Riffle/Pool/Glide Ratio Large Wood or Log Jam Presence Rapid Stream Assessment Technique Table of Contents (continued) A. Streamside Corridor Characterization........................................................15 1. Streamside Condition ...............................................................................15 Buffer Width Vegetative Cover Tree Canopy Plant Community Large Wood Debris / Recruitment potential 1. Floodplain Width and Plant Community ...................................................16 1. Outer Buffer Width and Plant Community ................................................16 1. Adjacent Landscape Character ..................................................................17 A. Casual Observations of Biological Indicators .............................................17 Macroinvertebrates Fish and Crayfish Birds and Other Wildlife Evidence A. Project Opportunities ....................................................................................18 Culverts & Barriers Channel Enhancement Bank Stabilization Vegetated Corridor Enhancement Preservation/Conservation J. Culverts and Stormwater Outfalls ................................................................18 ............................................................................................................................................... I. Data Sheet and Reference Field Sheets I. Plant Community Reference I. Project Opportunity Elements Rapid Stream Assessment Technique List of Figures Figure 1. RSAT Measurements Figure 2. RSAT Transect Channel Measurements Figure 3. Relative Levels of Riffle Substrate Embeddedness Figure 4. Representative Substrate Fouling Levels Figure 5. Buffer Measurement List of Tables Table 1. Stream Nomenclature Table 2. RSAT Substrate Size Classes Table 3. List of RSAT Water Clarity and Color Terms Table 4. List of RSAT Odor Terms I. Introduction The Tualatin Basin Rapid Stream Assessment Technique (RSAT) was developed to pro- vide a concise and accurate watershed scale assessment of stream health. This version of the assessment was modified to meet the needs of the Watershed 2000 inventory. The information gathered from the inventory is being used to address both Clean Water Act and Endangered Species Act issues facing the Tualatin Basin. The assessment represents an adapted version of Metropolitan Washington Council of Government’s RSAT (1996), which was a synthesis of US Environmental Protection Agency’s Rapid Bioassessment Protocols (Plafkin, et. al. 1989), the Izaak Walton League and Save Our Streams stream survey techniques (Kellog, 1992), US Department of Agri- culture Water Quality Indicators Guide: Surface Waters (Terrell and Perfetti, 1989), together with input from ecology professionals with many years of local stream survey experience. RSAT has been intentionally designed to provide a simple, rapid reconnaissance-level assessment of stream quality conditions and potential enhancements that may improve stream health. Major abiotic and biotic factors which influence overall stream quality have been placed into the nine following general RSAT evaluation categories: 1. Stream Flow Characterization 1. Stream Cross Section Characterization 1. Stream Channel Characterization 1. Water Quality 1. Physical In-Stream Habitat 1. Streamside Corridor Characterization Rapid Stream Assessment Technique 1. Casual Observations of Biological Indicators 1. Project Opportunities 1. Culverts and Stormwater Outfalls The field protocols outlined in Section II provide further detail regarding the methods of measurement and analysis of the categories noted above. Section III contains the data sheets and supporting reference sheets needed to complete the RSAT’s. Section IV and V contain plant community references and model project elements, respectively. Assessment Qualifications The assessment work should be performed by a professional trained in the field of hydrol- ogy, soil science, geomorphology, botany, fish/macroinvertebrate biology, ecology or other related science discipline. Rapid Stream Assessment Technique I. Tualatin Basin RSAT Field Protocols The protocols described herein represent an attempt to provide both general guidance and standardized procedures for "reading” the stream for tell-tale signs of overall quality and level of impairment. In addition to calibrating and properly maintaining water quality meters and other field equipment, it is important that RSAT survey team members cali- brate their eyes by reviewing other sites in the watershed and cross-comparing evaluation scores. Where more quantitative or intensive data is needed for study purposes (e.g., peb- ble count for enumerating substrate particle size) RSAT may be modified to accept the needed accommodation(s). The RSAT employs a rigorous field evaluation protocol in which over 50 physical, chemi- cal and biological parameters are measured. The RSAT transect includes the stream as well as the adjacent stream buffer which consists of the riparian corridor and /or flood- plain. The RSAT length represents information gathered up and downstream of the RSAT transect, and was measured to be 2 x bankfull width at the transect x 10 feet. The findings for the RSAT transect, along with the RSAT length are then linearly applied to the stream reach where the riparian and geomorphic conditions are represented by the RSAT infor- mation. Multiple RSATs must be gathered along the stream as the riparian and / or geo- morphic conditions change, in order to adequately represent the stream being studied. All the gathered information is transferred into a database and geographic information system (GIS). All the locations of field information collection are electronically logged by a glo- bal positioning system (GPS), to allow for repeat analysis at the same location in the future. The details of protocol elements are outlined in sections A-G. A. Field Survey Preparation, Planning, and Data Organization 1. Field Work Timing The assessment is best conducted between July and October, when stream flows are low and channel characteristics are visible. If significant storms occur over the course of the analysis, field work should be suspended until the stream returns to “normal” low flow conditions. 2. In-House Preparation Before heading out to the stream, the following preparatory map work and planning is recommended: a. Review existing watershed management plan, aerial photography, and stream water quality data, if available. b. Identify the stream(s) to be studied and determine their RSAT nomen- clature per Table 1. Assign a nomenclature, if none is available for the stream. Check to ensure the abbreviation is not already being used by another stream. Rapid Stream Assessment Technique b. Using a US Geological Survey 7.5 minute series quadrangle topo- graphic map, watershed plan map or equivalent, delineate the drainage area at the furthest downstream point to be surveyed. Then using either a planimeter, dot grid, or geographic information system (GIS) calcu- late the associated drainage area; b. Determine the general watershed land use(s) and approximate overall imperviousness level for the survey area using, whenever available, recent county/state zoning and land use maps or watershed plan infor- mation; b. Orient yourself with the RSAT definitions: Transects are the sampling locations perpendicular to the stream and extend out to the outer flood- plain or buffer area. RSAT length is the sampling area along the stream, upstream and downstream of the transect station with the extent based on the channel width x 10 feet. Stream reach is the geomorphically and ecologically discrete unit along the stream in which the RSAT transect and length data is applied (Figure 1). b. Pencil-in and number the proposed
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